Leadless pacemakers are used to sense electrical activity and/or deliver therapeutic pacing pulses to the heart. For some patients, one atrial pacemaker may be used in one atrium of the heart. In other patients, multiple leadless pacemakers may be used in at least one atrium and at least one ventricle of the heart. Each leadless pacemaker device typically includes two or more electrodes on its outer housing to deliver therapeutic electrical pulses and/or sense intrinsic depolarizations of the heart. Each leadless pacemaker may be positioned within a chamber of the heart and, in some examples, may be anchored to a wall of the heart via a fixation mechanism.
In dual-chamber, leadless pacemaker systems, two or more pacemakers in two or more chambers of the heart must be able to pace the chambers in synchronous fashion. At the same time, sending timing signals from one leadless pacemaker in one chamber of the heart to another leadless pacemaker in another chamber of the heart, as well as receiving and processing the delivered signals with the receiving pacemaker(s), consumes large amounts of battery power, thus decreasing the useful life of the leadless pacemaker devices.
Therefore, it would be desirable to have a dual-chamber, leadless pacemaker system that maintains a desired timing of its pacing pulses with minimal communication between pacemakers in different heart chambers. Such a system would help reduce battery consumption and thus extend the useful life of the system, while still achieving a desired pacing timing.